16900021 has 2 divisors, whose sum is σ = 16900022. Its totient is φ = 16900020.

The previous prime is 16899973. The next prime is 16900031. The reversal of 16900021 is 12000961.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16892100 + 7921 = 4110^2 + 89^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16900021 is a prime.

It is a super-2 number, since 2×16900021² = 571221419600882, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (16900031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8450010 + 8450011.

It is an arithmetic number, because the mean of its divisors is an integer number (8450011).

Almost surely, 2^16900021 is an apocalyptic number.

It is an amenable number.

16900021 is a deficient number, since it is larger than the sum of its proper divisors (1).

16900021 is an equidigital number, since it uses as much as digits as its factorization.

16900021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 19.

The square root of 16900021 is about 4110.9635123654. The cubic root of 16900021 is about 256.6231006808.

Adding to 16900021 its reverse (12000961), we get a palindrome (28900982).

The spelling of 16900021 in words is "sixteen million, nine hundred thousand, twenty-one".